1. Field of the Invention
The present invention relates to a device which is adaptable to all weapons or ammunition such as in particular artillery projectiles which are subject to aerodynamic base drag. The precise object of this device is to reduce the base drag in order to achieve an appreciable increase both in range and accuracy of ammunition provided with said device.
The device in accordance with the invention is contained within a specific package which is ready for use, which is independent of the ammunition to be equipped with said device and is provided with all the systems and means required for its operation. If so desired, the device can be mounted just before firing, as a function of the distance of the target to be hit, thus providing a simple solution to the problem of differential range of a round of ammunition. Thus the device in accordance with the invention is a veritable "kit" which is adaptable at any moment to any type of ammunition, very simple arrangements being required for fitting the device on a round of ammunition or projectile.
2. Description of the Prior Art
In order to increase the range of projectiles fired into the atmosphere such as, for example, shells fired by artillery pieces (guns, howitzers and the like), it is possible to adopt two systems:
additional propulsion; PA1 a gas generator of the type commonly designated as a "base bleed".
In the case of additional propulsion, the propellant charge is placed within a chamber of the projectile. As a result of combustion, the propellant chamber produces an additional acceleration of the projectile on its flight path. One disadvantage of this device lies in the fact that the acceleration at the start of the flight path reduces firing accuracy to an appreciable degree. To this is added an appreciable increase in mass of the projectile, with the result that the gain in range is not proportional to the additional energy consumption. Furthermore, since the length of projectiles cannot be increased inconsiderately for reasons of bulk and ballistics, the propellant charge is inevitably incorporated at the expense of the useful volume of the projectile.
The other device consists of a gas generator placed within a chamber at the base of the projectile. Combustion of said gas generator is initiated by a suitable igniter from the initial instant of flight of the projectile. The gases generated by combustion escape through an orifice formed in the combustion chamber at the base of the projectile. The discharge of hot combustion gases does not cause any active acceleration of the projectile and has the sole effect of filling the low-pressure volume which is formed at the rear end of the projectile by aerodynamic forces and produces base drag which in turn has the effect of reducing the range of the projectile to an appreciable extent. Since the base drag just mentioned is thus neutralized, the result thereby achieved is a considerable increase in the range of the projectile. The advantage of this device lies in the fact that the increase in range is achieved much more economically than by additional propulsion while being of the same order of magnitude (up to 30%). Furthermore, since the increase in range is obtained solely by filling of the aerodynamic low-pressure base volume and therefore without acceleration, firing accuracy is distinctly improved in comparison with the use of additional propulsion.
A device of this type is described in particular in French Pat. No. 2,328,938. This device forms an integral part of the projectile and consequently can neither be separated from this latter nor stored independently of the projectile for subsequent positioning on this latter, for example just before firing. Furthermore, even if it were possible to separate a device of this type from the projectile, it would prove impossible to fire the projectile since its base would not have sufficient strength to withstand the pressure generated within the tube of the gun or weapon used for firing.